Serum inhaled corticosteroid levels in patients with severe asthma.

There are no robust methods of assessing compliance to inhaled corticosteroid (ICS) therapy. Medication possession ratio calculated based on dispensed prescriptions is often used but does not account for whether the medication was taken, and if so correctly. We explored the feasibility of measuring serum ICS levels in patients with severe asthma on biologics.Patients with severe asthma approved for mepolizumab were invited. Patients were instructed to withhold their ICS on the morning of the first visit for spirometry, but to continue their prescribed ICS for the remainder of the study. Serum was taken approximately four hours after the morning dose. Beclometasone (Bec), Budesonide (Bd) and Fluticasone Proprionate (Fp) levels were measured via liquid chromatography-mass spectrometry at baseline then 12 and 52 weeks after initiation.23 patients were recruited to the study. Serum levels were below the sensitivity of the assay in over 37%, 22% and 6% of patients at baseline, 12 and 52 weeks respectively. Median serum levels increased from 12 to 52 weeks for Bec (206ng/L to 551ng/L, p=0.09, n=12), Bd (397ng/L to 1019ng/L, p=0.03, n=7) and Fp (33ng/L to 132ng/L, p=0.47, n=4).This is the first demonstration of serum levels of Bec, Bd, Fp measured longitudinally in patients on biologics. Serum ICS levels relate to drug administration time, which may allow dose-concentration curves to be illustrated in the future and subsequently an assessment of true compliance. We postulate that th...
Source: European Respiratory Journal - Category: Respiratory Medicine Authors: Tags: Airway pharmacology and treatment Source Type: research